Telephone-exchange system.



Y T. G MARTIN.

TELEPHONE EXCHANGE SYSTM. l v *x APPLICATION FILED JUNE 16, 1906. Patented m. 5,1915a T. G; MARTIN.' y TELEPHONE EXCHANGE SYSTEM.

' K APPLICATION FILED JUNE 18, 1906. 9123933 Patented Jan.5,1915

j SEEETS--BHEBT 2.

` ffwi T. G. MARTIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 16,1906.

Patented Jan. 5, 1915.

5 SHEET-SH-SHEET 3.

T. G. MARTIN. l TELEPHONE EXCHANGE SYSTEM.' APPLIGATION FILED JUNE 16, 1906.

191235339, Patented JaIL5, 1915.

5 SHEETS-SHEET 4.

T. G. MARTIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNEl 1G, 1906.

LMSQSSQ. Patented. m15, 1915..

l 5 SHEETS-SHEET 5.

narran sprarns entranti ormoni,

TALBGT Gr. MBTINVOF CHICAGO, ILLINOIS, ASSIGNB, BY MESNE ASSIGNMENTS, TO FIRST TRUST AND SAVINGS BANK, TRUSTEE, OF CHICAGO, ILLNOS.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

lPatented Jan.a 5, 1915,

To all whom it may concern:

Be it known that I, TALBOT G. lsiixu'rrn, a citizen of the United States of America, and resident of Chicago, Cook county, 111inois,lhave invented a certain nen1 and useful improvement in Telephone-Exchange Systems, ofl which the following is a specification.

My invention relates to telephone systems in general, but moreparticularly to automatic or semi-automatic telephone systems, and especially to extension or party line systems.

'i Generally stated, the object oi' my invention is to provide improved means for preventing interference between subscribers on the saine extension or party line.

lt vvill be seen that my present invention is in the nature of an improvement on the extension or party line telephone system disclosed in my prior application Serial No. 289,048, filed by me in the United States Patent Oliice on tbe 25th day of November', 1905. In said prior application asubstation relay is employed for removing the substation ground connection from the control of any extension or party line subscriber who attempts to use his telephone after the line is once temporarily appropriated for use by another subscriber" on the same line,A Also, in said prior application, the switchbook is connected Afor mechanically restoring the an mature of the said relay after the latter has been operated.

`My present invention, however, contem` plates certain improvements by which the switch-hook is relieved of this work, and

whereby the said ground controlling relay is restored, vby an electro-magnet or relay, which latter may be termed a releasing lay.

l also novv provide certain improvements in the first-selectors, together with certain novel combinations and circuit arrangements and details of construction tending to increase the general efficiency of a telephone system of this particular character, as will hereinafter more fully appear.

To the foregoing and other useful ends, my invention consists in matters hereinafter set forth and claimed.

Figure 1 shows'in diagram the circuits and apparatus involved when one substation of a telephone line is in connection with .mother substation of another telephone line.

line, the calling subscriber being shown at the left and the answering subscriber at the right. 1t will be understood, of course, that in this case it makes no difference whether a line is an extension line or a party line. The elements comprised in the said connection, shown in Fig. 1, are a calling substation #110, the first-selector A, the oeiitral battery B, the connector C, the called first-selector A1, the called substation #220, the party substation lD on the calling line, and the party substation E on the called The subscriber at substation D is shown locked out, having raised his switch'- hook after the subscriber #110 obtained control of the line. Fig. 2 is a similar' view showing the circuits and apparatus involved when a subscriber calls another subscriber on the same line. The line here represented is the calling line in Fig, 1, and in addition tothe substations :tt-110 and D the substation F #210 is also shown. The substation #110 is also the calling substation, While the called substation is the station F #210, the

substation D being again shown locked out for the same reason stated in connection with Fig. 1. Fig. 3 is a diagrammatic perspective view of the selector-switch A. Fig. 4 is a similar view of the connector C. ln these gures the central battery is shown in a number of places, but it Will be understood that'but one battery may be employed having its positive terminal preferably grounded at G. Figs. 5, 6, 7, 8 and 9 are detail views of the substation circuit controlling and restoring relaysllY and l, respectively, mounted upon a frame U 'The substation telephone equipment may be of any Well-known or approrcd type. The substation illustrated in Fig. 1 comprises the usual switch-hook 2, the receiver 3, transmitter 4, primary Winding 5 of the induction-coil 6, the battery 7, secondary winding S o1e the induction-coil 6, condenser 9, and ringer 10. The switch-hook has a number of cam-arms 11, 12, 13 and 14. The cam-arm ll'controlsthe springs 15 and 16; the cam-arm 12 controls the ground springs 17 and 18; the cam-arm 13 controls the springs 19, 20, 21, 22, 23 and 24; and the cam-arm 1l controls the release-springs 25,

2G and 27. The substati'cn signaling or Erickson & Erickson.

resented by the push-buttons 32. and 33, springs -34 and 35, contact-points 36 and 37, and ground pcst 38. The substation circuitcon'trolling relay H is provided with anarmature 39 for controlling the springs 40, 41, 42, 43 and 44. A latch 45 isprovided for locking the armature 39, which latch is controlled by the spring 46. The substation release-relay I is also provided With an armature 47 for controlling thearmature 39 of" the relay H, and for controlling the latch 45. lThe said relay I, by means of its armature 47, controls the energizing circuit ef the relay H through the medium of the springs 48 and 49. It Will be understood, of course, that the other substations herein shown are the same. The selector A may also, like the substation, be of any desired or approved generalcharacter. The type herein described is of the general classdisclosed in Patent No. 815,321., granted March 13, 1906, to Keith, Said selector is provide'd witha shaft 50 for carrying the line wipei-s 51 and 52 and the'private Wiper 53. The said shaft is operated vertically by the vertical magnet and may be raised to any 'y one of t'en pbsilxgions for placing the said Wipers on a gevel With. any one of the rows' of contacts of lie yline'hnd private banks 55 and 56, respectively. Being raised, the shaft may be iotatedbya rotary magnet 57. The" release-magnet 58 is employed for restoring the switch after it has been operated.. The

- vertical alnd rotary line relays 59 and 60, the

bridge-cut-olf-relay 61, the back-release-relay 62, and the privatemagnet 63 are auxiliaries for controlling the vertical, rotary and release magnets 54, 57 and 58. lVhen the call-l ing sub-criber operates the vertical line relay 59 by sending impulses from the substation through said relay, the vertical magnet 54 is operated, which latter then raises the shaft 50; and when the subscriber energizes the rotary line relay 60 the private magnet 63 is energized for operating the side switch `The said side switch is a step-by-step mechanism adapted to move from first to second position and from second to third postion.`` Zhen the private magnet 63 operates for the first time the side switch passes to second position, establishing an energizing circuit for the rotary magnet 57, which lat-ter then automatically operates to rotate V the shaft carrying the shaft-wipers 51, 52

and intofconnection with some suitable trunk-line; and as soon as the trunk-Ime 1s found the side switch K passes to third pos1- tion, destroying, therefore, the energizing' circuit of the rotary magnet, and connecting the subscribei"s line with a trunk-line. The selector-switch may be released by one of two methods-that is, either directlyl from the line, or over the seized trunk. In the former case the vertical and rotary line relays 59 and 60 are-energized simultaneously and a circuit is then set up through the release-magnet 58. This release, however, can

any subscriber from calling in on the line of the selector While the line is in use. y When a subscriber calls another subscriber on his own line the connection is completed by means of a connector, and unless special provision is made for the removing of 'the guarding potential that is established When the selector is first operated it would therefore be impossible for one subscriber to call another subscriber on the same line. To meet this requirement the selector is provided With a private normal relay 64 which removes the guarding potential at the instant that the connector controlled from a certain line starts to establish connectie With the same line.

The connector may be of any' suitable or approved type, such, -for instance, as a connector of the general type described in Patent No. 815,176, granted March 13.` 1906, to Keith, Erickson & Erickson. struction of the connector is quite similar to that of the selector, although the circuits of the former are quite different from those of the latterA The switch-shaft 65, the Wipers 66, 67 and 68, the line and private banks 69 and 70, the vertical and 'rotary line relays 71 vand 72, the vertical magnet 7 3, the rotary magnet 74, the release-magnet 75, the private magnet 76, and the sideswitch Lare similar to those of the selector. The confnector has a ringer-relay 77 for bridging 10o l The contime the'private magnet 76 operates to shift the side switch L to secondposition.- The shifting of the side switch removes the vertical magnet 73 from the control of the vertical line relay 71'and substitutes -therefor the rotary magnet 74. The rotary magnet docs not operate automatically, as is the case With the rotary magnet of the selector, but operates step-by-step in accordance with each electric impulse directed by the subscriber to operate the vertical line relay 7l the second time. When the rotary line relay .tresses Aagain actuated and the side itch L passes to third position, removing is operated the second time the private n a system is as follows: removes his receiver 3 he permits the switchhooh 2 to rise, removes the ringer 10 from across the line, substitutes instead the secondary circuit Comprising the receiver 3 and the secondary winding 8 of the induction- .coil t3, closes a local energizing circuit through the transmitterl 4, and primary im winding 5, and establishes a ground connection Vio the ground post 38 of theralling de id 'to the release-spring 25 and the contac y point 31 f the signalingv device.

The calling subscriber then proceeds by pressing the buttons 32 and 33 of the calling device, thereby operating the first-selector A, causing .the side switch to place the switch-shaft wipers'ii, 52 and 53 in connection with the trunknline leading to some connector C, and establishing a-guarding potential by way oI the private normal conductor 70 (Fig. 2) with the connector pribanlr-contact 80, and to all other private barniz-contacts that are connected .in multiple therewith. The said connector() se operated to carry its wipers 66, 67

' vi'fito en^"agemeifit with the desired 'the desired line is bhsy 'the conis well-known, is released by the y"al found the private con- Iii: theI connector is he calling lineto sig-- r of the calling line ay oil then removes i at the private bankan instant to permit the consa ish the connection. As soon e. is operated from sub- 0, lor instance, the switch-shaft d, and at the lirstjstep the a rings a and 81 are brought by placing the side of the c syn-ing 30 is connected in W hen o exi nl eter connection with vthe main battery B.

the side switch is in first position the said connection isestablished through the rotary e relay' G0; `when the side switch. is in ',sition through the vertical line when the side switch is in i through theA rotary line re- `e connector As soon as the c closed becomesimposother substation (such. as the and if? o interfere with the calling substation it because as soon as a switch-hook of one of the other substations D or F (Fig. 2) is raised an energizing circuit is established, through the ground controlling relay M of the interfering station, and the Vsubstation release ground ol the interfering station is thus cut, oli'. The interfering subscriber, finding he can malte no connection, and that the line is busy, will restore his receiver and thereby momentarily energize the releasing relay N. It will be noticed that it becomes possible to energize the said relay N after the cutoff-relayl M has been pulled up, since the springs 201 and 203 are now in contact, thus Aplacing the release-relay N .in connection with they release-spring 204. When the said spring is pressed onto the springs 20S and 207 an energizing circuit is then established through the line relays of the central office apparatus.

ln detail the operations and circuits are as follows: lf 'the subscriber-'at substation #110 (Fig. 1) Wishes to call the subscriber at substation #220, he removes his receiver and thus establishes connection between the ground terminal G1, ground post 38 of the calling device, release-spring 25, and contact-point 31 of the signaling device. He (the calling subscriber) lthen presses the button 32 twice and the button 33 of the callingdevice once; 'again the button 32 twice andthe button 33 once; and for the last time the button 32 ten times and thi` button 33 once. r1`he abovel ground circuit is established as soon as the switch cam l2 permits the ground springs 17 and 1S to come into contact. By pressing the button 32 twice the vertical line relay 59 of the selector A is energized twice, the current owing in each case lfrom the substation ground through the springs 4:4; and 43, ground springs 17 and 18 to the ground Post 38, thence to the spring 3l, vertical line conductor 83, side switch wiper 811, contact- 'point 85', conductors 86 and 87, vertical line relay' 59, bridgecutoffrelay springs 88 and 39 to the batterydead 90, thence through battery B to ground G. Each time that the vertical line relay 59 attracts its armature the line relay spring 91 is pressed onto the ground spring 92 and the vertical. magnet 54 in turn is energised. The path of' the current through the vertical magnet 5i is as follows: from ground G2 through the springs 92 and 91, conductor 93, private springs 94 and 95 to the vertical magnet, 511i, thence to p the battery-lead 90 and through battery B to ground G. Each time that the vertical magnet 154 is energized it attracts its armature 96, causing the vertical pawl 97 to engage one of the circular teeth 98, thereby raising the shaft one step at a time At the first step the release link 99 is disengaged from the double-dog 100, and the vertical dog 101 catches and as soon asthe shaft is raised the first step,

the switch-shaft 'springs' 80a and 81 close contact, extendingthe subscribers rotary.

line conductor 102l to the side switcliwiper 103. When the rotary button 33 is pressed the rotary line relay is energized by a flow of current from ground Gl at the substation to the ground post 38, thence to the spring 35, rotary linel conductor 102, switchshaft springs 80El and 81, side switch wiper 103, contact-point 101, conductor 105 to the rotary line relay 60, thence to the batterylead 90 and through battery B to ground G. The rotary line relay upon attracting its armature presses the spring 106 onto the ground spring 92, energizing the private magnet 63. .n

'lhe energizing circuit for the private magnet is as follows: Beginning from ground G2 it extends through the springs 92 and 106, conductors 107 and 108 to the private magnet 63, thence to the batterylead 90 and through battery B to ground G.

When the private magnet 63 attracts and releases its armature 109 the escapement-fin.- /ger 110 clears the teeth 111 and 112 and the side switch K passes to second position. The switch-sliaft having been previously raised two steps the switch-shaft wipers 51, 52 and 53 aie then-opposite the first contact of the second level of their respective banks.

. It may be assumed that the first nine trunks of the second level are busy, in which case the first nine contacts of the second level of the private bank 56 are connected to ground. When the sigle switch passes to second position 4the side switch wiper 113 engages the`contact-point Ill-l and sets up an energizing circuit for the rotary magnet 57. The current flows from ground G3 to the' contact-point 111-, side switch wiper 113,

' conductor 11i. to the rotary magnet 57, passing through the interrupter-springs 116 and 117 to the battery-lead 90 and through battery B to ground G. The shaft 50 will be rotated one step at the first impulse of the y rotary magnet, and as a result the private magnet 63 is energized when the private wipei' 53 strikes the first grounded Contact.

The circuit extends from ground G of battery B through whatever selector is occupying the first trunk to the first contact of the second level of the private bank 56, thence through the private wiper 53, conductor 118, back-bridge-relay 62, conductor 119, side switch wiper 120, contactpoint 121, conductors 122 'and 108 to the private. magnet 63, thence to battery-lead 90 and through battery B to ground G. The private magnet 63 will, by keeping its arma-A ture 100 attracted, lock the side switch K in second position until the private wiper passes the last busy contact, at which time the energizing circuit for the private magfsition of the second level ofthe line bank The side switch Wiper 120 having at the saine time engaged the contact-point 125 a guarding potentialV is established from ground G4 to the private wiper 53 and, therefore, to the tenth contact of the sec.- ond level of the private bank 56, and to the connector private bank-contacts corresponding to the line that terminates in the selector A, by way of the private normal conductor 7 9.

Assume that the seized trunk-conductors 126 and 127 and the trunk release conductor 128 leading from the line and private banks 55 and 56 terminate in the connector C, as shown in Figs. 1 and 2. Having established connection with the connector C the calling subscriber by pressing the vertical button 32 twice again energizes the vertical line relay 71 of the connector. The current passes from ground G1 to the vertical line conductor 83, thence through the side switch wiper 84 to the line wiper 51 and to the vertical trunk-conductor 126. It then flows through the line relay 71 to the battery-lead 90 and through battery B to ground G. The vertileo cal line relay 71' is energized twice and presses the spring 129 onto the ground spring 130. As a result the vertical magnet 73 is energized twice, and the shaft 65 is raised two steps, carrying the shaft wipers 66, 67 and 68 ,opposite the first contacts of the second level of their respective banks. The energizing circuit for the vertical magnet 73 extends from ground G5 through the springs 130 and 129, conductor 131, private springs 132 and 133, conductor 134, side switch wiper 135, contact-point 136 to the vertical magnet 73, thence to the batterylead 90 and through battery B'to ground G. Each time that the vertical magnet 73 becomes energized the armature 137 is attracted, as in the first-selector, and the shaft 65 is operated as described. rThe rotary button 33 is next pressed once and .the rotary line relay 72vof the connector is energized in turn. The energizing current fiows from ground G1 to the rotary line conductor 102, through the switch-shaft springs .80 and 81 to the side switch wiper 103, line wiper 52 to the rotary trunk-conductor .127, thence through the lconductor 138, .ringer-relay springs 139 and 140, conductor 141 and through the rotary line relay 72 to the battery-lead 90 and through battery B to aies met 74 under the control of the vertical line relay 71. The subscriber' then presses the vertical button 32 ten times and again energizes the vertical line relay 71 each time.

'li he rotary magnet 7 e is thus energized ten times by a flow of current from ground to the side switch wiper 135, thence through the contact=p`oint 144, vrotary magnet 74 to the battery-leadH-QO, and through battery B to ground GL The rotary magnet by attrac.` s ing its armature 145 ten times rotates the shaft 65 lso as to carry the shaft-Wipers 66, 67 and 68 into enga gement with the trunle line leading from the tenth contacts ot' the second level of their respective banks` Pressing therotary button 33 for the last time the subscriber energizes the rotary line relay 72 once, and also the private magnet 7 6 once, thus shifting the side yswitch L to third position and thus connecting thel subscribers Xtended line conductors 126 and 127 to the normal conductors 146 and 147, respectively. The conductor 126 is connected with the conductor 146 through the condenser 148 of the connector, conductor 1119, ringer-relay springs 15() and 151, side switch Wiper 152, contact-point 153, conductor 154, line'wiper 66 to the conductor 1116. 1t will be seen that the conductor 127 connects Vwith the normal conductor 147 through the condenser 155.

conductor 156, ringer-relay-springs 157 and- 158, side switch Wiper 159, contact-point`,a160, conductor 161 and Wiper 67. At the'instant that the connector side switch L passes to third position not only is the subscribers line placed in connection With the called sub1 scribersline, as shown, but a guarding potential is set up over the seized line to prevent other connectors :trom interrering. As

shown, the guarding potential is established from ground G to the contact-point 162, side switch Wiper 163, conductor 164: and private Wiper 68 to the contact-point engaged by the said private Wiper and to all other contacts in multiple. Such guarding potential not only protects the seized line but also energizes the bridgecut-od-relay 165 of the called selector A1 for disconnecting the vertinal line relay 166 of the said selector from the ha Jervieml 90. This is necessary in order n 'e the balanced condition of the l Le energizing circuit through said errnits' a flow of. current to 'bridge-cutoff-relay 165,

` flows from groun pass trom ground G at the connector to the private Wiper 68, thence over the private normal conductor 167 of the vprivate normal relay springs 168 and 169, conductor 170, side switch wiper 171, conductor 172 to the 70 thence to batterylead and through battery 13 to ground G. The said relay 1.65 upon energizing separates the springs 173 and 1711, with the desired result.

The calling subscriber vnow having established connection presses the signaling button 28, thereby grounding the spring 29 -on the contact-point 81, and as a result energizing the vertical linerelay 71. The current G1 through the springs 14 and l13 and through the ground springs 17 and 18 to the contact-point 31, thence 'through the spring' 29 and through the springs 19 and 26 to the contact-point 36 of the calling device, thence -through .the spring 31- to the vertical line conductor 88, energizing the vertical line relay 71 over the usual path. The vertical line relay'again presses 'the springs 129 and 130 and energizes the ringerereiay 77. The established circuit extends trorhground through the said springs 180 and 129 to the side switch wiper 185, thence to the contact-point 175, ringer-relay 77 to the battery-lead 90 and through battery B to ground G. r1`he vringerrelay 77 then presses the springs 151 and 158 onto the springs '17 6 andr 177, thus bridging the ringer-generator across the side switch Wipers 152 and 159, and, there- 100 fore, across thecalled subscribers line. The ringing current then passes to the vertical line conductor 178, .spring 17 9, contactpoint 180, switch-hook 181, spring 182, ringer 183, condenser 184, contact-point 185, spring 186 to the rotary line conductor 187 and, of course, back to the generator 78. The subscriber at the substation #220 upon hearing the signal Will remove his receiver and bridge his secondary circuit across the 11o line in the same manner as described in connection with substation #110. It will be understood, of course, that the ringing cui rent also passes through the ringer at the substation E; but the bell at that station 'being out of tune with the particular cur? groupwvhich is provided with ringing current suitable for operating the ringer at `the desired station. The talking circuit over Which the calling and called subscribers `converse is clearly shown by the 841 of the selector A, vertical line wiper 51,

conductor 126, condenser 148 of the connec- Vtor C, conductor 1119, ringer-relay springs 150 and 151, side switch Wiper 152, vertical line Wiper 66, vertical normal conductor 146, .vertical line conductor 178, spring179, contact-point 180, through the secondary Winding and the receiver at the substation #220 back to the contact-point 185, spring 186, rotary line conductor 187, rotarynormal conductorl147, rotary line Wiper 67, side switch Wiper 159, ringer-relay springs 158 and 157, conductor 156,' condenser 155, conductor 127, wiper 52 of the selector A, side switch Wiper 103, switch-shaftsprings 81 and 80", rotary line conductor 102, spring 35., contact-point 37, condenser 9 back to the receiver 3. If the substation D attempts to use the line 'after the subscriber .7E/:,110 has operated his selector A and thereby closed. the switclrshatt springs 80EL and 8l, the ground controlling relay M Will be energized at the instant that the switch-hook closes the springs 188 and 189 before the springs 190 and 191 are separated, since the rotary lineconductor 102 is cop'nected to main battery B through some ofthe relays already described, depending upon the stage Aof the call.

The relay M will be energized by a flow of current from ground G7 through `the springs 192 and 193, winding of the relay M, springs 190 .ind 191, and through springs 188 and 189 to the contact-point 191 of the calling device, thence through the spring 195 to the rotary line conductor 102.

1f the side switch of the selector A is in first position the circuit will' be completed through the rotary line relay 60 and to the battery-lead 90 and to battery B; if in the p second position through the vertical line relay 59 to the battery; and if in the third positionlthrough the rotary line relay 72 of the connector C to the batttry-lead 90 andV to the battery. The relay M then iiergizes` or pulls up, and the armature 196 is locked by the latch 197, owing to the pressure of thev spring 198. As a result the springs 199 and 200 are forced apart and the spring 201 is shifted from engagement with the spring 202 into engagement with the spring 203, thus placing the release-relay N in series with the ground release-spring 204.

When the springs 199 and 200 are forced `apartv the substation ground circuit is delease-spring 208, contact-point 191 and.

spring 195 to the rotary line` conductor 102, and again over a multiple circuit from the spring 208 to the spring 207, contact-point 209, spring 210 to the Vertical line conductor 83. The circuit then, of course, extends from the said vertical and rotary line con`- ductors through the line relays of the switches, depending upon the position of the side switch of the selector A, to the battery B.

The paths taken from the rotary line conductor 102 to the main battery have already been pointed out and the path` taken from the vertical line conductor 83 to the battery, when thelside switch is in first position, is through the vertical line relay 59 of the selector A; andwhen the side switch is in second position there is no connection to the battery B by way of the vertical line-conductor, but only by way of the rotary line conductor; and when the side switch is in third position the battery B is reached through the vertical line relay 71 of the connector C. r'ilhese circuits, of course, have -alreadybeen traced. At this instantthat .from returning to its normal position too quickly by the lug 213 to prevent the springs 203 and 201 fronrseparating prematurely.

Not only does the armature 211 control the .armature 196, but also the springs 193 and 192, so as to prevent the relay M from energizing at a time when the arm-ature 196 Y should be free to regain its normal position, namely at the time when the relay N is energized, for otherwise the relays M and N would be energized in multiple. l The resistance of such multiple connection would be very 10W and, in fact, low enough to cause trouble by the raisingand lowering of the switch-hook. Referring now to the called line, it will be noticed that there are no relays across the line between the called subl scribers line and the connector after the tion E, cannot interfere with the established connection, since it makes no difference how much they operate their calling mechanism or signaling orringing devices. Grounding either the vertical or rotary line conductors 178 or 187, or both, can energize no apparatus at the central oliice; therefore, it is not necessary to provide means for cutting oit the ground connection of the substations on the called line.

After the subscribers :#:110 and :#:220 are through talking the subscriber #110 may release the switching apparatus by restoring his receiver 8 to the switch-hook 2 and thereby pressing the release-springs 25, 26 vand 27 into contact. By pressing the release springs together the vertical and rotary line conductors 83 and 102 are grounded simultaneously from the ground terminal G1, and as a result the vertical and rotary line relays 71 and 72 of the connector C are energized simultaneously. Thepath from ground 'G1 to the said conductors 83 and 102 is as folloWsiFrom ground G1 through the springs 44 and 43,'through the ground springs 17 and 18 and through the springs 42 and 41 to the release-spring 25, thenceby way of the release-,springs26 and' 27 tothe said line conductors.

Energizing the-line relays 71 and 72 off the connector simultaneously forces the trunk-release-springs 214 and 215 together and establishes an energizing circuit that comprises the release-magnet 7 5 of the connector C and back-release-relay 62 ofthe selector A. The current through this circuit may be traced from ground Gtat the selector A to the contact-point 125, side switch ,wiper 120, conductor 119, back-release-relay 62, conductor 118, private wiper 53, trunk release conductor 128, trunk release springs 214 and 215 to the release-magnet 75, thence to the battery-lead andV through battery B to ground G. As a result the release-magnet 75 attracts its armature and -releases the connector-shaft and side switch; and the back-release-relay 62 of the selector upon bringing the springs 216 and 217 into engagement establishesy an energizing circuit through the release-magnet 58 of thertirst-selector, which release-magnet 58 thenl attracts its armature-218 in orderthat the release-link 99 may latch and hold the double-dog 100 in readiness to restore the switch when the release-springs at' the substation are opened. It will be evident, of course, that as soon as the connector private wiper 68 leaves the engagingv contact the energizing circuit through thehizitlge-cut` orelay 165 of the selector A1 is broken, the said relay is restored to normal condi tion, returning the vertical line relay 166 to normal connection with the battery-lead 90. As soon as the said springs separate the energizing circuit for the line relays 71 72 of the connector is destroyed so that the trunk release springs 21/1 and 215 separate to de'e'nergize the release-magnet 75 oir the connector, the back-release-relay 62 of the first-selector, and the release-magnet 58 of the said selector.' When the release-rnagnet 58 denergizes the release-armature 218 returns to normal position, carrying the double-dog to normal position, ,and-permitting the shaft 50 to be restored at the same time that the side switch K is restored.

It is thus clear how a subscriber of one party line may call a subscriber of another party line. 1t will now be explained how a subscriber of one party line may call another subscriber of the same party line. For instance, referring to Fig. 2, it may be assumed that the subscriber at Vvsubstation v:ft-,E calls the subscriber at substation` #210. In making the call the subscriber'at substation #110 removes his receiver 8 from the switch-hook 2 and then presses the bute ton 32 twice and the button 33 once; again the button 32 once and the button once; and for the last time the button 32 ten times and the button 33 once. By operating his calling device in this manner the shaft' 50 et the selector A, as already described, is raised two steps and the wipers are rotated along the second level of the line and private banks. v Assuming again that the first nine contacts are busy, the wipers will arrive on the tenth contacts of the second level of the line and private banks, from which a trunkn line leads to the connector C, as already described. It will be remembered that as soon as' the selector side switch passes to third position the side switch wiper 120'engages the contact-point 125 and a guarding potential is established at the connector private bankcontact 80. The subscriber in continuing to operate his calling device raises the connector-shaft to the rst level and then rotates it ten steps, carrying the wipers into engagement with the normal conductors 219 and 220 that lead back onto the calling line.

It has been -described how after the selector has trunked to the connector the connector rotary vline relay 72 is energized :each time that the rotary line conductor 102 is grounded. 1t will be noticed, furthermore, that the private norniallrelay of the selector A is energized attire saine time. The current for energizing said relay 6: tiews from the substation ground G1 to the rotary line conductor 102, when the rotary button 33 is pressed, thence through the switchshaftsprings 80B and 81, side switch wiper 103, contactpunt 124;, tothe saidrelay, @a

icc

brought his connector wipers into engagement with the normal conductors 219' and.l

220, as described, by pressing the vertical button 32 ten times, corresponding to the third digit of the number 210, and at the instant thathe grounds his rotary line conductor 102 by pressing the button 33, he not only energizes the private magnet 76, but vhe alsov energizes the private normal relay 64 and cuts off the guarding potential from the contact-point 80'. As soon as the impulse is interrupted the private' magnet 76 as well as the private normal relay 64 denergize; but the private springs 223 and 224 separate and the side switch escapes to third position before the guardingI potential is returned to the contact-point 80.

Were not the guarding potential thusremoved the connector would be released at the instant-that the private springs 223 and 224 come into contact upon the energization of the private magnet. The energizing circuit for releasing the connector would extend from the contact-point 80 (which is grounded) to the private wiper 68, thence to the conductor 164, side switch wiper 163, contact-point 225, conductor 226,. private springs 223 and 224, release-magnet 75 to the battery-.lead 90. The release-magnet 75 upon energizing will, ofcourse, release the connector. This is also the vcase whenever the connectorI attempts to establish connection with a busy line. Having established connection with his own line, as described, the calling subscriber signals back on his own line and rings the bell of the deff-lied station :#210, since the ringer-generator 78', controlled by the connector C,'produces a current of a frequency that will affect only the bell of the substation` it210 of the calling line, as'previously explained. The subscriber :fr/:210 upon answering removes his bell 'from across the line and substitutes instead his receiver 227 in series with the` secondary winding 228 of the induction-coil 229. Clearly, then, the two subscribers may "converse over the line conductors 83 and 102I which connect them. It will-be under* stood, of course, that when the subscriber at substation F removes the receiver from the switch-hook the lock-out relay of this sub- 'station also operates. If while the two subscribers are connected or at any time when the selector A. has been operated the sub-v scriber D, for' instance, attempts to use the `line he 'will be locked out in a manner that has been previously described--that is, since the rotary ,linerconductor 102 is connected to main battery the relayvM will be' energized as in the previous case. If he restores his receiver he will in turn energize the release-relay. N, which will restore his apparratus to normal chnditio'n. After the calla result, of course, the vertical and rotary line relays 71 and- 72 of the connector will again energize simailtaneously, establishing :1n-energizing circuit through the releasemagnet 75 of the .connector and the backrelease-relay 62 ofthe selector A. The connector-shaft is atyonce restored, as well as /the connector side tswitch. The back-releaserelay 62, as is well known, in turn energizes the release-magnet 58 of the selector, and when the release-springs 25, 26 and 27 of the substation separate Vthe switches are then fully restored in the usual and well-known manner. The substation relays may be mounted upon a separate and independent base, as shown in Figs. 5, 6, 7, 8 and 9. The

relays H and I are inclosed in 'a frame O l .upon an upwardly-projecting section 232 of the frame O, very clearly shown in Fig. 9.

' Ihe said armature has a downwardly-pro-j 1yecting section 233 which controls the 'springs 40, 41 and 42 in one group and the springs 43 and 44 in another group. The springs 41 and 43,. since they bear continually upon the said section 233, act as restoring springs for the said armature 39. The armature 47 in a similar manner ispivoted upon another upwardly-extending projection 234, clearly shown in Fig. 5, which armature, like the armature 39, is provided with a downw'ardly-projecting section 235 for controlling the springs '48 and 49.

The spring 49, being always in 4engagement with the section 235, acts as a restoring spring fog the armature 4.7. The member 236 of the armature for controlling the latch" 45 isclearly shown in Fig. 5. The said latch, as shown in Fig. -5 and also in Fig.,7;"

is pivoted between the lugs 237 and 238 and l is controlled by tht-'A retractinU-spring 46. The two faces 239 and 240 of the frame O are made rigid by means ot the cross-piece r 241 whichv is supported bv the screws 242 Iand 243. The lateral member 244 that projects from the armature 47 of the relay I is designed to control the armature 39 ofthe relay H,.so that when the arm A236 removesA the link 45 from the armature 39 the latter secured can be of any suitable material, ot' course, and is provided with terminals 2&5 tor receiving the ends of the conductors lead-ing to and from the relays H and l and the springs they control.

.T he; .substation coils H and l may be of s any suitable resistance, but it'is found that good results are obtained when they are wound to thirteen hundred ohms each.- The private normal relay (il of the first-selector is wound to a resistance of live hundred ohms. The battery can be of volts.

From the foregoing it will be seen that I provide an improved arrangement whereby one partyA line subscriber cannot interfere with the use of the line by another subscriber who is on the same line and who is already in'possession of the line 'for either talking or switching or signaling purposes.

'thus makin-g it possible to conveniently ernapparatus shown in ploy desk telephone sets in connection with a party line system of this particular character. With such provision no extension or .party line subscriber can in any way intertere with the use of the line by another subscriber already in possession of the line.

This application shows and describes apparatus similar rto that which is shown and which is being claimed in certain other of my co-pending applications. However, the

from that shown in the above mentioned copending application in certain respects, towit: each substation on a party .line 1n the present application is provided with a pa1r of magnets, which magnets work in conjunction to control the lock-out mechanism of each subscribers individual substation: in that one of the line relays of the individual first selector switches-is permanently connected to one pole of the battery; that the private normal control relay, that is, the relay which controls the private normal, is permanently connected to one pole ot the battery and is excluded from the talking circuit. The claims are restricted to one or moreotl these features. l

`What l claim as my invention iszl. In an extension or party linetelephone system, atelephone line, a plurahy -of subscribers telephones connected therewith, au-

this application diiers and in nected therewith,

tomatic switches, a ground connection at each telephone; meansY by which said ground connections may be employed for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground controlling relay for each telephone, and a release-relay for each ground controlling relay, said relays being excluded from the talking circuit.

2. In an extension or party line telephonesystem, the combination of a telephone line, a plurality ci subscribers telephones connected Itherewith, automatic switches, a ground connection at each telephone, means by which said ground connections may be employed for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground controlling relay for each telephone, and a releaserelay for each ground controllingr relay,

each release-relay provided with means for mechanically restoring itsassociated ground controlling relay tonormal condition.

3. ln an extension or party line telephone system, the combination of a telephone line,

a plurality of subscribers telephones connected therewith, automatic switches, a ground connection at each telephone, means by which said ground connections may be employed for transmitting electrical impulses ovcr the telephone line to operate said automatic switches, a ground controlling relay for each telephone, and a releaserelay' for each ground controlling relay, each release-relay provided with means for both electrically and mechanically controlling its associated ground controlling relay.

l. ln an extension or party line telephone system, the combination of a telephone line, a plurality of subscribers telephones connected. therewith, automatic switches, a ground connection at each telephone, means by which said ground connections may be employed -for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground controlling relay for each telephone, a release-relay for each ground controlling relay, each ground controlling relay provided with an armature, and means for latching said. armature in its attached position, each releaserelay provided with means .for-unlatching said armature.

In an extension or party line telephone system, the combination of a telephone line, a plurality of subscribers telephones conautomatic switches, a ground connection at each telephone, means by which said ground connections may be employed for transmitting electrical.. impulses over the telephone line to operate said automatic switches, a ground controlling relay for eaclrtelephone, and a release-relay for each ground controlling relay, each ground controlling relay having grounded llt) TE. t@

energizing circuit includingboth sidesof the telephone line, said energizing circuit controlled by its allotted release-relay.

G. In a telephone exchange system, a telephone line, a subscribers telephone connect ed therewith, automatic switches, .a ground connection. r* the subscribers telephone, means by which the subscriber may use the said ground connection for transmitting elec- A trical impulses over the telephone line to operate said automatic switches, a r'el-ay.con trolling,r said ground connection, said' relay provided with an armature, means for latching said armature in its attracted position,

' and an electro-magnetic device forv unlatching said armature.-

7. In a telephone exchange system, a tele-l phone line, a subscribers telephone connected therewith, automatic switches, aground.

connection associated Witi the Asaid telephone, means by which the subscriber mayl use the said ground connection for transmitting electrical impulses over the tele# phone line to operate said automatic switches, a relay controlling said ground connection, an energizing circuit for said relay, and another relay for controlling said switches, means by which the subscribersl may employ, said ground connections -for transmitting electrical impulses over the fsaid telephone line to-operate said automatic switches, a ground controlling relay for each telephone, an electro-magnetic device allotted to each relay, provided with means for controlling the relay, and a subscribers switch-hook for each telephone, eachswitchhook provided with connections for electrically controlling its allotted electro-mag-v netic device.

`9. In a telephone exchange system, a telephone line, a plurality of subscribers telephones connected therewith, a switch-hook for each telephone, a ground connection for each telephone, automatic switches, means b y which the subscribers may employ the said ground'coiincctions for transmitting electrical impulses over the telephone line .to operate said automatic switches, a ground controlling relay foreach telephone, each relay provided with an armature, means for latching the armature in its attracted position, and means for electrically unlat'ching orrestoring said relays by the down? ward movement of their respective switchliooks.

10. In avtelephone exchange system, a telephone line, a siibscribers telephone connected therewith, an automatic switch, a ground connection allrtted to the telephone, means by which the subscriber may employ said ground connection for transmitting electricalimpulses over the telephone line' to operate said switch, a plurality of grounded line circuits including the saidv ground connection, and a plurality of relays associated with -said telephone and provided with means for controlling said circuts.

11. In a telephone exchange system, an automate first-selector switch provided with bank-contacts, a wiper adapted/to engage said contacts, means for operating said Wiper, abattery, a relay permanently conpole of said battery, and a talking circuit excluding the Winding of said relay.

12. In a telephone exchange system, the combination of an automatic first-selector switch provided with bank-contacts, awiper nected inseries between said wiper and one adapted to engage said contacts, -.means for automaticiirst-selector switch provided with bank-contacts, vertical and rotary line' wipers 'for engaging said contacts, means- 4for operating said wipers, a battery, a relay permanently connected in series between the rctary line Wiper and one pole of said-battery, and a pivate normal circuit controlled by said relay. l

14. In a telephone exchange system, 'the combination'of 'an automatic first-selector switch-provided with bank-contacts, verti` cal and rotary line wipers forvengaging said contacts, means for operating said wipers, a battery, a relay permanently connected in series between the rotary line wiper and one pole of said battery, a private normal 'cir` cuit controlled by said relay, and a talking.

circuit excluding the winding of said relay.

15. In a telephone exchange' system, an automatic first-selector provided witha pair of normally bridged relays, a battery having one pole grounded and the other .pole

connected with thebridge at a point between said relays, the battery being perinanently4 connected with the Winding of one relay, and means for disconnecting the other v relay from the battery.

16. In 'a telephone exchange system,

trunk-lines, an automaticA trunk-selecting switch mechanism provided with a pair of normally bridged. line relays, a battery having one pole grounded and the other pole connected to the bridgeat a point between said relays, one relay having its vwinding permanently connected with the battery, and a 'bridge-cut-olf-relay for severing the connection between the other relay and the battery.

17. In a telephone exchange system, a

y otherrelay and the battery.

telephone line, trunk-lines, an automatic trunking switch individual to the said telephone line, said switch` provided witha pair of normally bridged line'relays, a bat- 18. In 'a telephone exchange system, an

automatic switch provided with a Apair of normally bridged line relays, a battery having' one pole grounded Aand the otherpole normally connected tothe bridge at a point between said relays, one relay having its winding permanently connected y'with the battery, and means for severing connection between the other relay and the battery.

19. In a telephone exchange system, the combination of lan 4automatic first-selector provided witha pair of normally bridged relays, a battery having one pole grounded and the other pole connected with the bridge at a point betweenl said relays, the battery being permanently-connected with the winding oone relay, means for disconnecting the other relay from the battery,'a talking circuit, and means for disconnecting both relays from the talking circuit.

20. In a telephone exchange system, the combination of trunklines, an automatic trunk-selecting switch mechanism provided with a pair of normally bridged line-relays, a battery having one pole grounded and the other pole connected to the bridge at a point between said relays,4 one relay having its winding permanently connected with the battery, a bridge-cut-oifrelay for severing the connection between the other relay and the battery, a talking circuit, and means for disconnecting both relays from the talking circuit.

21. In a telephone exchange system, the combination ot a telephone line, trunk-lines, an automatic trunking switch individual to the saidvtel'phone line, said switch provided with a'pair of normally bridged line relays, a battery having one pole connected with ground and the othcrpole connected to the bridge at a point between said relays, one relay having its winding permanently connected with the battery, a bridge-cut-o'd-relay for severing the connection between the other relay and thc battery, a talking circuit, and means for disconnecting both relays from the talking circuit.

22. In a telephone exchange system, thc combination ot an automatic switch liro- \'ided with a pair oi normally bridged liuc relays, a battery having one pole grounded aud the other pole normally connected to the bridge at a point between said relays, one relay having its winding permanently conlll..

nected with the battery, means for severing connection between the other relay and the battery, a talking circuit, and -ineans for disconnecting both relays from the talking circuit.'

23. In an extension or party line telephone system, the combination of a telephone line, a plurality of subscribers telephones connected therewith, automatic switches, a ground connection at each telephone, means by which said ground connections may be employed for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground controlling relay for each telephone, a release-relay for each ground controlling relay, said automatic switches including connectors, meansft'or permitting a connector to establish connection with the calling telephone line, and means by which the calling subscrbermay then produce an audible calln signal at the telephone of the called subscriber on the same line.

24. In an extension or party line telephone system, the combination of a telephone line, a plurality of subscribersl telephones connected therewith, automatic switches, a ground connection at each telephone, means by whichsaid ground connections may be employed for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground controlling relay torv each telephone, a re lease-relay for each ground controlling re- ,lay, each release-relay pxbvi'ded with means for mechanically restoring its associated ground controlling relay to normal condition, said automatic switches including connectors, means for permitting a connector to establish connection with the calling telephone line, 'and means by which the calling subscriber may then produce an audible callsignal at the telephone of the called subscriber on the same line.

25. In anA extension or party line telephone system, the combination of a tele phone line, a plurality ol'v subscribers telephones connected therewith, automatic switches, a ground connection at each telephone, means by which said ground connections may be employed for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground controlling relay for each telephone, a 'release-relay for cach ground controlling relay, each release-relay provided with means tor both electrically and mechanically controlling its associated ground controlling relay, said automatic switches including connectors, iur-.ans 'lor permitting a connertor to establish connection with the calling telephone line, and means by which thc ral'- ing subscriber may then produce an audible call-signal at the telephone of the called sub scr1ber on the same line.

y26. In an extension or party line-telel phone system, the combinationv of a telephone line, a pluralit i of subscribers telephones connected t erewith, automatic switches, a ground connection at each telephone, means by which said ground connecv tions may be employed for transmitting elecerate said automatic switches, a ground contrical impulses over the telephone line to optrolling relay for each telephone, a releaserelay for each ground controlling relay, each ground controlling-relayproyided with an arma-ture, means for. latching :said armature in its attracted position, each., release-relay provided with means for-unlatching said armature, said automatic switches vincluding connectors, means for permitting a connector toestablish connection with the calling telephone line,'aiid1'neans b lwhich the calling subscriber may then pro uce an au'diblecallsignal at thetelephone ofthe called ysubscriber on the same line.

,27. In an extension or party4 line telephone system, the. combination 'of a telcphone line, a plurality of subscribers telephones connected therewith, v'automatic switches, a ground connection at .each telephone, means 'by which said ground connections may be employed for transmitting electrical impulses over the telephone line to operate said automatic switches, a ground; controlling relay for eachy telephone, a release-relay 'for each ground controlling relay, each ground controlling relay having a grounded energizing circuitvincluding both sides of the telephone line, said energizing circuit controlled by. :its allotted release-relay,`said automatic switches including connectors, means for permitting' a 'connector to establish connection with the calling teleplione'line, and means by which the calling subscriber may then produce an audible cal lsignal at the telephone of the called sub-'f `operate said automatic switches, a ground controlling' relay for each telephone, an electro-magnetic device allotted to each relay, p'r -fided with means "for controlling the relay, a subscribers switch-hook for each telephone, each switch-hook provided with connections for electrically controlling its allotted electro-magnetic device, said automaticl switches including 4 erativel thesa'i relays, for restoring said relays to connectors, "means for-permitting a connector toestabw lisli lconnection with the calling telephone line. and means by whieli the calling'sub--' `scriber may then produce an audible callsignal at the telephone of the called subscriber on the same line.

29. In a telephone exchange system, the combination of a telephone line, a plurality of subscribers telephones connected therewith, a switch-hook for each-telephone, a

ground connection for each telephone, automatic switches, means by which the sub-v scribers may employ `thesaid ground connections for transmitting electr'cal impulses over the telephone lineftoo'pera matic switches, a ground controlling relay for each telephone,eacli` relay provided with an armature, means or -latchingfthe arrnature inuitsattracted' v.position,"ff `neansfor electrically -unlatchingvor restoringsaid relays by the' downward)moyementof their .respective switch-hockey:4 said automatic switches inclu'dingconnectors, lmeans tor permitting al 'cennectoiff' to'Jl establish connection with 4the,calling--telephone line, and

' means by whichv the calling subscriber may then producean'audible call-signal at the telephone of the called subscriber on the same line. y l l A .30.'Anv automatic .party-line telephone system comprising cut-off and release relays at each of the substations onv a party' line, the substatious being in multiple, substation apparatus governed thereby, and means including automatic switchestor lextending 4connection from said party-line.`4

31. ln a telephone system, a party-linea plurality of substations on said line, the substntions being in multiple, a relay at each substation, said relays controlling the use of the line for make-and-breakimpulse-transmitti'ng purposes, and electromagnets opconnected with the armatures of normal'position. l

32.' In a telephone system, a party-line, suitable means forextending connection to said au-toor'froxn said line,'and a plurality of relays for each substation on said party-line, controlling circuits thereof, said relays adapted to prevent interference between the ditferent subscribers on the, sameline in extending a` connection therefrom, said relays having no control over the talking circuit.

'33. In a telephone system, a line, a plurality of* telephones connected therewith, means-for extending a connection there- 'from,.an'dfmeans for preventing interference between the different subscribers in extendinga connection from said line, said means comprising a pair of substation-'controlled relays foreach telephone, one relay of. each pair controlling the energizing circuit through the other, said relays having no control over the talkingcircuit.

34.*#111 an extension or party-line telephones'ystenrtvv 'a telephone line, a' plurality of` s'ubscribekis telephones connected theremotionto select groups and rotary motion to connect with a line in any selected group, a ground connection at', each telephone,

means by which said ground connections" Atelephone line, a subscrihers telephone connected therewith, automatic switches having vertical motion to select groups and rotary motion 'to connect with a line in any selected group, a ground connection at the subscribers telephone, means `by which the subscriber may use the said ground vconnection for transmitting electrical impulsesover the telephone line to operate said automatic switches, a relay controlling said ground connection, said relay provided with an armature, means for latching said armature in its attracted position, and an electromagnetic device for unlatching said armature.

36. ln a telephone exchange system, a

telephone line, a subscribers telephone coni nected therewith, automatic switches having vertical motion to select groups and rotary motion to connect with a'line in any selected group, a ground connection associated with the said telephone, means by which the subscriber may use the said ground connection for transmitting electrical impulses over the telephone line to operate said automatic switches, a relay controlling said ground connection, an energizing circuit for said relaytand another relay for controlling saidv energizing circuit.

37. In Ia telephone exchange system, a telephone line, a plurality of subscribers telephones connected therewith. a ground connection allotted to each telephone, automatic switches having Vertical motion to select groups and rotary motion to connect with a line in any selected group, means byl which the subscribers may employ said ground connections for transmitting electrical impulses over the said telephone line to operate said automatic switches, a groundcontrolling relay'tor each telephone, an electromagnetic device allotted to each relay, provided with means for controlling the relay, and a subscribers switch-hook for each telephone, each switch-hook provided with connections for electrically controlling its allotted electromagnetic device.

38. ln a telephone exchange system, a telephone line, a plurality of subscribers telephones connected therewith, a switchhook for each telephone, a ground connection for each telephone, automatic switcheshaving vertical motion to select groups and rotary motion to connect with a line in any selected group, means by which the subscribers may employ the said ground connections 'for transmitting electrical impulses over the telephone line to operatesaid automatic switches, a ground-controlling relay for each telephone, eachrelay provided with an armature, means for latchinlr the armature in its attracted position, anu-means tor electrically'unlatching or restoring said relays by the downward movement of their respective switch-hooks.

39. ln a telephone exchange system, ay telephone line, a subscriber-s telephone connected therewith, an automatic switch having vertical motion to select groups and rotary motion to connect with a line in any selected group, a ground connection allotted to the telephone. means by which the subscriber may employ said ground connection for transmitting electrical im ulses over the telephone line to operate said switch, a plurality of grounded line circuits including the said ground connection. and a plurality of relays associated with said telephone and provided with means for controlling said circuits. f

40. ln a telephone system` a party-line,

a plurality'of relays for each of the subvstations thereof, the substations being in multiple, automatic switches controllable over the said line. and means whereby said relays preclude interference between the .subscribers in the use ot' said switches.

41. ln an automatic telephone system, a party-line, a plurality of relays for each ot the substations thereof` the substations being in multiple, hook-switches controlling the circuits of said relays. an automatic switch, and means at said substations 4ior controlling said switch lor extending connection from said Vparty-line.

4211i a telephone system, a telephone line having one side thereof normally open at the exchange or central station, a substation on said line provided with a pair ot relays, means controlled from said substation on said line for closing said normally open connection in the talking circuit. an energizing circuit for one ot said relays which includes the said normally open connection,

a vertical and rotary switch shaft. and operating circuits controlled by said relay for controlling said shaft.

Signed by me at Chicago, Cook county,

@epica of this patent may he obtained 'for :ve cents each, by addressing the Commissioner of Patents.

Washington, In. G.

It is hereby certified that in Letters Patent No. 1,123,339, granted January 5,

1915, upoh the application of Talbot G. Martim of Chicago, Illinois, for an improvement in Telephone-Eriehange Systeme an error appear-` in the printed specification requiring correctionl as follows: lage'Q, line 116, for the Word attached read attracted; and that the said LettersiPatent should be read with this' correction therein that the same may conform to the record of the case in the Patent Otee. i l

Signed and sealedl this l26th dav of January, A. D., 1915.

'i R. F. WHITEHEAD,

Acting Commissioner of Patents.-

. [SEAL] 

